1. Summary of the Invention
This invention relates to thermotropic, wholly aromatic polythiolesters capable of forming an anisotropic melt and a process for preparing the polythiolesters.
2. Description of the Prior Art
It is well known in the art that a broad spectrum of polythiolesters can be prepared by reacting various ingredients. Thus, for example, in U.S. Pat. No. 2,510,567, polythiolesters are prepared by reacting dimercaptans with the acid chlorides of dibasic acids. Similarly, U.S. Pat. No. 2,870,126 describes a process of preparing polythiolesters by reacting organic dithiols with the acid chlorides of dibasic acids.
Linear polythiolesters are disclosed in U.S. Pat. No. 3,254,061. These polymers are obtained by reacting the phenyl esters of dicarboxylic acids with dimercaptans at elevated temperatures. The reaction liberates phenol which is removed from the reaction mixture. The resulting polymer can be melt extruded into fibers and then cold drawn and processed into high tenacity yarns.
Liquid thiolester-terminated polymers are described in U.S. Pat. No. 3,705,882. The thiolester polymers are prepared by reacting liquid mercaptan-terminated polymers with anhydrides, esters or carboxylic acids.
Although prior art of the type discussed above discloses various polythiolesters, the search has continued for high strength, high stability, polythiolesters which may be processed into superior fibers, films and other types of shaped articles. This invention was developed as a result of that search.